For senior and staff frontend candidates
The Mentoxis Guide
JavaScript, async, the browser, quality, UI building and the senior and staff rounds, in learning order, with a priority on every topic.
61 pagesFree PDF
What's inside
From how JavaScript runs your code to the staff-level rounds, in the order to learn it
Every topic starts in simple words, then builds up through examples and diagrams. Each one carries a priority, shows what it builds on and what it leads to, and most list the companies where candidates reported it.
- 6stages, in learning order
- 38topics
- 52practice questions40 predict-the-output, 12 quick checks
- 13solved coding problems, with tests
- 15diagrams
- P0–P2priority on every topicP0 Must know · P1 High · P2 Good to have
6 stages, in learning order
- Stage 1
Language core
Closures, this, prototypes, copying and memory
20 practice questions
- Stage 2
Asynchronous JavaScript
The event loop, promises, debounce, queues and retry
14 practice questions
- Stage 3
Browser platform
The rendering pipeline, events, storage and networking
5 practice questions
- Stage 4
Quality at scale
Core Web Vitals, accessibility and security
6 practice questions
- Stage 5
Building UIs
CSS, React, TypeScript and the machine coding round
7 practice questions
- Stage 6
Staff-level rounds
Frontend system design, behavioral and leadership, and DSA in JavaScript
Who it's for
Senior and staff frontend engineers preparing for product-company loops
You already ship production frontends. Product-company loops still open with JavaScript theory and output questions, then add the rounds that decide senior and staff offers. The guide covers both, in the order that compounds.
What changes at senior and staff level
Machine coding (UI building)
Build a working UI from a short brief against the clock, then extend it as new requirements arrive, handling loading, errors and keyboard use.
Frontend system design
Design a product like a news feed or chat app out loud: requirements, architecture, data model and interfaces, then the performance and accessibility trade-offs.
Behavioral and leadership
Tell real stories clearly: leading without authority, handling disagreement, learning from mistakes and the scope of your impact.
All on top of the JavaScript theory every loop starts with.
Sample pages
Look inside before you download
Three of the guide's 61 pages. Select a page to open it full size in a new tab.
(opens full size in a new tab)How to use this guide 
(opens full size in a new tab)Scope and closures 
(opens full size in a new tab)The event loop
Free practice
Practice all 52 questions interactively, with progress tracking
Every predict-the-output and quick-check question from the guide, in learning order. Answer, check yourself and pick up where you left off.
Company tags in the guide are reported by candidates in public interview write-ups. They are not official questions from those companies.